1. Field
The present disclosure relates generally to an interface and, in particular, to an interface for transferring signals. Still more particularly, the present disclosure relates to a method and apparatus for transferring a signal between rotating components.
2. Background
A spacecraft may be used for a number of different purposes. For example, a spacecraft may be used for communications, observation, meteorology, navigation, planetary exploration, and other suitable purposes. A spacecraft may be unmanned or manned. A spacecraft may be, for example, without limitation, a satellite, a space shuttle, a launch vehicle, a space station, or some other suitable system or machine.
It may be desirable to have a portion of the spacecraft remain in a fixed direction, while another portion of the spacecraft may be moved relative to the fixed portion of the spacecraft. For example, with a dual-spin spacecraft, the spacecraft may have a continuously rotating section and a fixed section. The continuously rotating section may be referred to as a spinning section, while the fixed section may be referred to as a despun section.
The despun section may be pointed towards a particular object or location. For example, the despun section may be pointed towards the earth, the sun, or some other object. The spinning section produces angular momentum and gyroscopically stabilizes the attitude of the spacecraft. The spinning section also may be covered with components, such as solar cells. In this manner, the solar cells may be partially illuminated by the sun at all times in a manner to provide power to the spacecraft.
The despun section may have antennas or other equipment that may need to be continuously pointed to a particular location, such as a location on the earth's surface.
These two sections may be coupled to each other by a bearing and power transfer assembly (BAPTA). The axis of this bearing and power transfer assembly may be parallel to the spin vector. The spin vector is the vector around which the spinning section turns or spins. In these examples, this axis may be referred to as a rotation axis.
Electronics, sensors, and/or other devices may reside on both the spinning section and the despun section of the spacecraft. Information may be transferred across this interface. This information may include, for example, without limitation, data, images, commands, programs, and/or other suitable information.
The transfer of information between a spinning section and a despun section of a spacecraft may be accomplished using a series of conductive rings and contact brushes. The conductive rings also may be referred to as slip rings. These components may be integrated into an electrical contact ring assembly within the bearing and power transfer assembly. For example, the rings may be located on an inner portion of the bearing and power transfer assembly that rotates within a housing containing brushes that contact the rings as they rotate within the housing. This contact may provide for a transfer of information from one side of the interface to another side of the interface.
The conductive rings and brushes may be constructed from a number of different types of materials. A coin silver is commonly used for a bearing and power transfer assembly. Further, these designs may require a lubrication system in order to operate for the desired period of time. For example, a satellite may be required to operate for 15 years or more in orbit. These types of systems may increase the expense of a satellite, increase the weight of a satellite, and may decrease the satellite's reliability.
Therefore, it would be desirable to have a method and apparatus that overcomes the issues described above as well as possibly other issues.